Optically pumped lasers can provide output having wavelengths between ultra-violet and far infrared regions of the electromagnetic spectrum. Current optically pumped lasers include atomic and molecular lasers. Pump sources for optically pumped lasers can include flash lamps, semi-conductor lasers, light emitting diodes, solid state lasers, gas lasers, dye lasers, and/or any optical pump source having appropriate wavelengths (e.g., neon: 640.4 nm, argon: 811.7 nm, krypton: 811.5, and xenon: 882.2 nm). Diode lasers can provide higher output powers and higher efficiency in operation compared to flash lamps. For example, diode pumped alkali lasers (DPAL) can be provide high output powers (e.g., over 1 kW output power from a cesium DPAL).
Optically pumped lasers can operate by pumping a ground state of an atom or a molecule to an excited state that either lases or undergoes collisional transfer to a nearby excited state that subsequently lases. FIG. 1 is an exemplary diagram 100 representing multiple states of a gas (atoms or molecules) that is optically pumped. The gas begins in a first ground state (1). The gas is optically pumped (e.g., by a diode) and transitions to a second excited state (2). In the second excited state (2), the gas collides further exciting the gas to a third excited state (3). In the third exited state (3), more collisions occur and the gas continues to have increasing energy, which eventually causes the gas to transition to a fourth excited state (4) of lasing. While optically pumped lasers can lase, they can be limited to gas species types that have ground states that are capable of transitioning by optical excitation.
Additional optically pumped lasers that can lase with the use of rare gas atoms (e.g., argon, krypton, and/or xenon) are available. These lasers typically optically pump from one excited state to another excited state that then lases. These lasers have only operated in a pulsed mode and usually do not operate at atmospheric pressure. Pulsed mode lasers are only “on” for a brief period of time, for example, a few nanoseconds to a fraction of a nanosecond. Therefore, pulsed mode lasers are typically not efficient at delivering a steady output beam. For some applications, e.g., Laser Identification and Ranging (LIDAR), pulse mode is desired, for many other applications, e.g., medical diagnostics, laser machining, and/or other laser material interactions, a continuous wave output beam is desired. Additionally, rare gas atoms are chemically stable and typically do not react with any surface in the laser including the optics. This can enable a lasant to be used indefinitely in a sealed system or readily flowed in a sealed system.
Therefore, it is desirable to lase rare gas atoms with an optical pump in a continuous mode. It is also desirable to lase rare gas atoms at atmospheric pressure.